Coercivity Enhancement by Grain Boundary Diffusion Process to Nd-Fe-B Sintered Magnets

Hirota,; Nakamura,; Minowa,; Honshima,

doi:10.1109/intmag.2006.374941

Cited by 12 publications

(12 citation statements)

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“…The potential shortage of minor metals such as Dy and Tb for Nd magnets is regarded as a national crisis. In addition, our research group recently reported on a grain boundary diffusion alloying method that applies rare earth compound to the magnet surface and diffuses Dy or Tb into magnet through the grain boundary (Nakamura et al , 2005; Hirota et al , 2006). This new technique has become a focus of attention because it can reduce the additive quantity of Dy and Tb.…”

Section: Prospect For Future Magnet Developmentmentioning

confidence: 99%

Rare Earth Magnets: Conservation of Energy and the Environment

Minowa

2008

Resource Geology

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Rare earth magnetsPermanent magnets have improved with regard to performance dramatically over the last fi ve decades and they have become essential in modern life and industry. Thus, our lives depend directly or indirectly on the function of permanent magnets.The permanent magnets, which are currently used in various kinds of industrial equipment, are approximately divided into two categories: the ferrite magnet and the rare earth magnet. Ferrite magnets are oxide magnets composed of mainly ferric oxide. Although they do not have excellent magnetic properties, they are produced in large quantities worldwide because of their low cost and consequently have good cost performance.In contrast, despite the relatively high cost, nowadays rare earth magnets are widely used in various high-performance devices due to their superior magnetic properties. The strength of rare earth magnets exceeds those of ferrite magnets by approximately 10-fold, but the price is also approximately 10-fold that of ferrite magnets. Accordingly, as far as the cost performance of the magnet itself is concerned, there is no meaningful difference between these two types of magnets. It is expected, however, that the overall performance of equipment, for example cost reduction by downsizing of the equipment or reduction of power consumption by improving of the energy effi ciency, can be improved. The rare earth magnets are indispensable in the design of products that realize miniaturization, high performance and energy saving. Nd magnetsRare earth magnets are divided into two categories, that is, the SmCo-type rare earth magnets and the NdFeB-type magnets (hereinafter referred to as Nd magnets). With regard to current production, more than 98% of the rare earth magnets are the Nd magnets; it can be said that a rare earth magnet is synonymous with an Nd magnet. In addition, there are two types of the Nd magnets: sintered magnets and bond Thematic ReviewRare Earth Magnets: Conservation of Energy and the Environment Takehisa M inowa Magnetic Materials Research Center, Shin-Etsu Chemical, Echizen, Fukui, Japan AbstractRare earth sintered magnets (Nd magnet) have been used in many applications such as computer and industrial equipment, automobile manufacturing and many others. They are highly effi cient and reduce energy consumption because of their superior magnetic properties. The element dysprosium (Dy) contained in the Nd magnet is important and indispensable. It improves the stability of the Nd magnet by enhancing the coercive force of its magnetic properties at high temperature. Dy is not so abundant. The rapid growth of the Nd magnet may result in Dy shortage. Exploration for new deposits of Dy is desired.

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Section: Prospect For Future Magnet Developmentmentioning

confidence: 99%

Rare Earth Magnets: Conservation of Energy and the Environment

Minowa

2008

Resource Geology

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“…To avoid this resource scarcity issue, there are two ways to improve coercivity with reduced or no HREEs; (1) utilizing the grain boundary diffusion (GBD) process [5,6], and (2) controlling the microstructure. The GBD process has been applied for sintered Nd-Fe-B magnets to effectively reduce HREE usage by more than 50%.…”

Section: Introductionmentioning

confidence: 99%

High performance hot-deformed Nd-Fe-B magnets (Review)

Hioki

2021

Science and Technology of Advanced Materials

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“…In 2000, Park et al proposed a promising way of grain boundary diffusion (GBD) to enhance the coercivity of thin Nd-Fe-B sintered magnets [8]. Lately, [9][10][11][12][13][14][15][16][17][18]. By annealing Nd-Fe-B sintered magnets, coated with micron-size TbF 3 particles, Nakamura et al [9] achieved a coercivity enhancement from 0.9 to 1.7 MA/m in the magnets without sacrificing their remanence.…”

Section: Introductionmentioning

confidence: 99%

Magnetic domain switching in Nd–Fe–B sintered magnets with superior magnetic properties

Yue

Liu

et al. 2018

Materials Research Letters

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Nd-Fe-B sintered magnets with a giant intrinsic coercivity of 47.1 kOe and a high maximum energy product of 38.5 MGOe have been prepared via a combination of conventional sintering techniques and novel grain boundary diffusion process. Microstructural observations show that the Nd 2 Fe 14 B main phase grains in the magnets exhibit a core/shell type rare-earth elements distribution, where Tb enriched (Nd,Tb) 2 Fe 14 B phases are formed in the surface regions of the grains. Magnetic domain observations indicate that these modified surface regions strongly restrain the nucleation process of reversed magnetic domains, leading to a remarkable enhancement of the coercivity and overall magnetic performance of the magnets. IMPACT STATEMENT Nd-Fe-B sintered magnets with an unprecedented overall magnetic property have been fabricated with a novel approach, and the origin of magnetic property enhancement was elaborated via magnetic domain observation.

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Coercivity Enhancement by Grain Boundary Diffusion Process to Nd-Fe-B Sintered Magnets

Cited by 12 publications

References 1 publication

Rare Earth Magnets: Conservation of Energy and the Environment

Rare Earth Magnets: Conservation of Energy and the Environment

High performance hot-deformed Nd-Fe-B magnets (Review)

Magnetic domain switching in Nd–Fe–B sintered magnets with superior magnetic properties

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